We propose to study the relative roles of the carotid sinus baroreceptors, the aortic arch baroreceptors, the cardiothoracic volume receptors, and renal arterial pressure in the regulation of renin release in the conscious dog, both normotensive and hypertensive (benign and malignant), on normal and low sodium intake. We shall also examine factors which stimulate or inhibit renin release from isolated, cultured glomerular cells. Finally we plan to study the relationships of the various endocrine factors which regulate blood pressure in the rat with diabetes insipidus.